Valley County, in Idaho, sits in USDA hardiness zone 6a — a band that supports both cool-season staples and warm-season crops chosen to fit the local frost window.
Among the crops suited to this profile: pumpkin, blackberry, california poppy, and zucchini. The site-level story — soil, sun, drainage — decides the rest.
Valley County lies within the Central Idaho Mountains — a regional growing area with its own character.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
Valley County holds more than one microclimate.
Soils and elevations shift across Valley County, so your frost dates and drainage aren't the county average. Enter your address and we'll score 1,086 plants against your land's actual soil, sun, and frost.
We read public map data around Valley County — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Valley County — the short answer
Valley County, Idaho: USDA zone 6a, about 94 days between hard freezes, across 2.3M acres.
- USDA zone
- 6a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Jun 14
- NOAA 1991–2020 Climate Normals, 28°F
- First hard freeze (28°F)
- Sep 16
- NOAA 1991–2020 Climate Normals, 28°F
- Days between freezes
- ~94
- NOAA 1991–2020 Climate Normals, 28°F
- County area
- 2.3M acres
- US Census TIGER/Line 2025
Every figure names the dataset it came from. Hard-freeze dates are county 28°F normals: light frosts run a few weeks past them, and tender transplants usually wait 2–3 weeks after the last hard freeze.
Hardiness Zone Range
Zone 6a is Valley County's average, not your lot's — a low corner or a tree line moves it. Against Valley County's 94-day season, see what your own ground reads.
Heat in Valley County
Across a year, Valley County accumulates about 578 growing degree days above 50°F, about 913 fewer than the middle Idaho county — no other Idaho county banks fewer. Degree days are the heat a crop actually gets to work with — more of them is more room to ripen a long-season crop before the freeze closes the window.
Grounded in PRISM Climate Group, Oregon State University — 1991–2020 monthly normals
Soil in Valley County
Across Valley County, the ground is predominantly Inceptisols, where Pyle, Koppes, and Bryan are the most extensive named soil series. The soil is generally somewhat excessively drained with a coarse sandy loam surface. Topsoil pH runs about 5.8–6.3, moderately acidic. Rainfall drains through hydrologic group A soils.
Soil order
Inceptisols
Drainage
Somewhat excessively drained
Hydric soils
6%
Soil still varies lot by lot — soil types explained.
How the ground varies across Valley County
The USDA soil survey maps 34% of Valley County as somewhat excessively drained — but another 57% drains differently: 32% well drained, 14% excessively drained.
Pyle is the most extensive named soil at 13% of mapped acres, then Koppes (11%) and Bryan (11%).
Which of them your own lot sits on is a parcel question, not a county one. Check your address for the survey at your boundary.
What this means for growing in Valley County
Each reading below is measured for Valley County itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Drainage
MeasuredThe dominant soils across Valley County are somewhat excessively drained, in hydrologic group A — ground that drains quickly.
The upside is soil you can work early in spring and roots that never drown; the cost is that fast-draining ground dries out fast and leaches nutrients away before plants can use them.
Work in compost and mulch to hold moisture and feed, and water more often in short doses than deep and rarely.
USDA NRCS SSURGO
Surface pH
MeasuredTopsoil across Valley County runs about pH 5.8–6.3, close to neutral.
This is the range most vegetables prefer — one correction you probably do not have to make, which is genuinely good news for a new bed.
Keep it there with compost rather than lime or sulfur, and only amend if your own soil test says otherwise.
USDA NRCS SSURGO
Season length
MeasuredValley County runs about 94 days between hard freezes — a short growing season.
Long-maturing crops like melons, sweet potatoes, and winter squash can run out of runway before the first hard freeze, ripening late or not at all.
Lead with fast-maturing varieties, and stretch the season on both ends with cold frames, low tunnels, or a greenhouse.
NOAA 1991–2020 Climate Normals
Winter hardiness
MeasuredValley County sits in USDA hardiness zone 6a.
The zone sets which perennials, shrubs, and fruit trees live through an average winter here — a plant rated for a colder zone is a safe bet, one rated warmer needs winter protection or gets treated as an annual.
Match perennials and fruit to the zone before you buy, so nothing you plant is a gamble against the cold.
USDA PHZM 2023
The kind of country Valley County is in
Valley County sits in the Idaho Batholith — EPA Level III, inside the wider Northwestern Forested Mountains. One consistent ecological setting across the whole county.
What Grows in Valley County
We scored all 1,086 plants against Valley County's own USDA zone 6a and its own 94-day season between hard freezes, using the same matching engine that runs a full parcel report. These cleared both. Sun, soil pH and drainage vary lot by lot — those are the parcel questions below. Each card opens that plant's Idaho profile.
Is it too late to plant in Valley County?
For most of the year, no — what changes is which crops still fit the days remaining. Cool-season crops can go in from around May 17; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Jun 14 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Sep 16 — long-season crops need about 90 days of runway, quick greens only 30. When the window is tight, the fall moves are quick ones — baby greens, radishes, and garlic set for next season.
Documented around Valley County
- monarch butterfly1 documented records
Sighting records, so they follow observers as much as insects.
What gets applied to farmland in Valley County
USGS estimates 3,039 lb of Glyphosate on Valley County farmland in 2019, its largest by weight, ahead of Metribuzin (1,157 lb) and Dimethenamid-p (882 lb).
Farmland across the whole county, not any one lot. Check your address for the site-by-site record.
Safe to Grow Here?
What the federal record shows across Valley County — and how to grow with it.
We checked the federal record across Valley County — 433 documented sites across 7 of the 9 source types we track.
The most significant on record: 6 Superfund sites. Sites tracked in EPA's Superfund program — from assessment-stage CERCLIS entries to confirmed National Priorities List cleanup sites.
Valley County carries one of the heavier federal records we track — and that's not a verdict on your yard. Proximity to a documented site is information, not a diagnosis: nothing here says any particular parcel is affected. It does earn one concrete step — before food beds go in the ground, a professional soil test tells you exactly what you're working with, and raised beds with clean imported soil grow well almost anywhere in the meantime.
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
What's on the federal record near Valley County
Closest first, across Valley County. Listing isn't leaking, and distance isn't exposure.
- Silver CliffMining · 7.2 mi
- Silver Cliff LodeMining · 7.2 mi
- Name UnknownMining · 7.3 mi
- Pioneer Group ProspectMining · 8.3 mi
- Golden GateMining · 8.7 mi
- Copper King ProspectMining · 9.0 mi
- Copper KingMining · 9.0 mi
- Babbitt MetalMining · 9.5 mi
- HARP OIL COUnderground Storage Tanks · 9.7 mi
- PARKS YELLOW PINE MERCHANTSUnderground Storage Tanks · 9.7 mi
- Antimony Ridge MineMining · 10.3 mi
- Dunkin ProspectMining · 11.4 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Valley County's center, not your beds. Run your own address for what's upwind of you specifically.
Environmental Intelligence
The counts behind that headline — every source type on the record near Valley County.
Sources Checked
across Valley County
Severity Distribution
across Valley County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Valley County, two things run higher than the national average across Valley County — Mining (270 sites) and Superfund (6 sites). Knowing it is half the work — and it's nothing a thoughtful grower can't plan for.
Mining: Mining sites — both historic and active — can leach heavy metals (arsenic, lead, cadmium, mercury) into soil and water for centuries after operations cease.
Superfund: Superfund sites represent the most severe contamination in the federal system.
Test soil for heavy metals (lead, arsenic, cadmium, mercury) — this is essential near any mining site.
Commission professional soil testing before any food production (test for heavy metals, VOCs, and SVOCs).
Check your specific parcel in Valley County
Get exact proximity distances to contamination sources for your specific parcel — plus soil, sun, drainage, and 1,086 plant recommendations.
25+ data sources read at your address, not the Valley County average
Your land is one point inside Valley County
Everything above resolves to Valley County as a whole — one PHZM band and one county frost record, read across 2.3M acres. Your parcel is one point inside that footprint. Slope, tree cover, a low spot that pools cold air, and what is in the soil are all resolved at the address, and none of them are visible at county scale. That is the honest boundary of this page, and the reason the next step is a reading of your own ground rather than a better county average.
Your Lot vs the Valley County Average
Valley County Average
- ●USDA Zones 6a, averaged across Valley County
- ●One soil character for all of Valley County
- ●Frost dates read at Valley County's scale: Jun 14 to Sep 16
YOUR Parcel
- ✓Your exact zone, not Valley County's 6a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Valley County
Pull a site-specific report for your exact address in Valley County, Idaho — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Valley County averages can't show:
We read public map data around Valley County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Valley County average
How we know this about Valley County
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, read at county grain; hard-freeze dates from NOAA 1991–2020 28°F normals at this county’s own record where one resolves, and the labelled statewide window where none does; soils from the USDA NRCS SSURGO survey, area-weighted across the county’s own map units; boundaries and acreage from US Census TIGER/Line 2025; the contamination and pesticide records from the federal sources named in their beats above. Where Valley County carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about Valley County
When does frost risk typically end in Valley County?
The last hard freeze (28°F) in Valley County typically lands around Jun 14, per NOAA 1991–2020 climate normals — earlier than the light-frost dates most charts quote. That marks the hard freeze, not the last light frost — lighter frosts keep biting past it, which is why tender transplants here wait until about Jul 5.
How long is the growing season in Valley County?
Measured between 28°F hard freezes, Valley County sees about 94 frost-free days — roughly Jun 14 through Sep 16, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Jul 5 to Sep 2, about 59 days.
Is the soil safe to grow vegetables in Valley County?
The federal record around Valley County runs heavier than most — 433 documented sites, mostly Mining entries (270), the nearest Mining record about 7.2 miles out — so test the soil before planting food in the ground, and raised beds with clean imported soil grow well in the meantime. Even here, proximity to a documented site is information, not a diagnosis of any one yard; the contamination map shows exactly what's recorded and where.
How do gardeners stretch the season in Valley County?
With about 94 frost-free days between hard freezes, Valley County rewards the classic extension moves: floating row cover buys roughly two to four extra weeks at each shoulder — on this season that is a working window nearer 122 to 150 days — and cold frames or low tunnels buy more. Starting transplants indoors ahead of the Jun 14 hard-freeze normal stretches the season without touching the calendar.
Everything above is measured at Valley County's scale — its 6a band and its 94-day season. Your yard writes its own version of Valley County's numbers: we read soil, sun, drainage and frost at your exact address. Try it for 14 days — no card required.
Will It Grow Here?
Zone fit is the first question — each answer below reads Idaho's frost window, season length, and soil profile against the plant's real requirements.
What this page reads at Valley County’s own scale
9 of the readings below were taken at Valley County's own scale — its own ~94-day span between 28°F freezes, the 3 most extensive soil series mapped here and 433 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- Valley County's own USDA hardiness band, zones 6aUSDA PHZM 2023
- Valley County's own 28°F hard-freeze dates and its ~94-day span between themNOAA 1991–2020 Climate Normals
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in Valley CountyUSDA NRCS SSURGO
- 433 documented contamination sites inside the county boundary, distance-sorted from its center — the closest Mining record about 7.2 miles outFederal environmental registers
- Valley County's boundary and the 2,345,675 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 6a and a ~94-day seasonGrowable Ground crop-matching engine
- Valley County sitting wholly inside the Idaho BatholithUS EPA Level III Ecoregions
- Open occurrence records documented in Valley County for a tracked speciesGBIF derived datasets (CC0 / CC BY 4.0)
- Which agricultural compounds go onto Valley County farmland, and roughly how muchUSGS NAWQA EPest county estimates
Inherited from a wider read
- The growing challenges every Idaho grower plans around — written at state scale, so they stay on the state guidefrom Idaho
What this page can’t tell you
- How the season shifts across Valley County — the ~94 days above is one reading at its centre; the 12 towns below each carry their owntowns in this county →
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Valley County's 2,345,675 acreswhy one lot differs from the next →
- Which of those 433 documented sites actually reaches your soil — that needs your address, the wind, and the groundwater directionhow we read the record →
- Where cold air settles, which slopes face the sun, and which way the wind runs on your own ground — none of it survives being averaged over Valley Countyread your own land →